Browsing by Subject "c2d small clouds"

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Revealing The Millimeter Environment Of The New FU Orionis Candidate HBC722 With The Submillimeter Array
(2012-08) Dunham, Michael M.; Arce, Hector G.; Bourke, Tyler L.; Chen, Xuepeng; van Kempen, Tim A.; Green, Joel D.; Green, Joel D.
We present 230 GHz Submillimeter Array continuum and molecular line observations of the newly discovered FU Orionis candidate HBC722. We report the detection of seven 1.3 mm continuum sources in the vicinity of HBC722, none of which corresponds to HBC722 itself. We compile infrared and submillimeter continuum photometry of each source from previous studies and conclude that three are Class 0 embedded protostars, one is a Class I embedded protostar, one is a Class I/II transition object, and two are either starless cores or very young, very low luminosity protostars or first hydrostatic cores. We detect a northwest-southeast outflow, consistent with the previous detection of such an outflow in low-resolution, single-dish observations, and note that its axis may be precessing. We show that this outflow is centered on and driven by one of the nearby Class 0 sources rather than HBC722, and find no conclusive evidence that HBC722 itself is driving an outflow. The non-detection of HBC722 in the 1.3 mm continuum observations suggests an upper limit of 0.02 M-circle dot for the mass of the circumstellar disk. This limit is consistent with typical T Tauri disks and with a disk that provides sufficient mass to power the burst.
The Spitzer Survey of Interstellar Clouds in the Gould Belt. II. the Cepheus Flare Observed With IRAC and MIPS
(2009-11) Kirk, Jason M.; Ward-Thompson, Derek; Di Francesco, James; Bourke, Tyler L.; Evans, Neal J., II; Merin, Bruno; Allen, Lori E.; Cieza, Lucas A.; Dunham, Michael M.; Harvey, Paul; Huard, Tracy; Jorgensen, Jes K.; Miller, Jennifer F.; Noriega-Crespo, Alberto; Peterson, Dawn; Ray, Tom P.; Rebull, Luisa M.; Dunham, Michael M.; Harvey, Paul
We present Spitzer Infrared Array Camera (IRAC; similar to 2 deg(2)) and Multiband Imaging Photometer for Spitzer (MIPS; similar to 8 deg(2)) observations of the Cepheus Flare, which is associated with the Gould Belt, at an approximate distance of similar to 300 pc. Around 6500 sources are detected in all four IRAC bands, of which similar to 900 have MIPS 24 mu m detections. We identify 133 young stellar object (YSO) candidates using color-magnitude diagram techniques, and a large number of the YSO candidates are associated with the NGC 7023 reflection nebula. Cross-identifications were made with the Guide Star Catalog II and the IRAS Faint Source Catalog, and spectral energy distributions (SEDs) were constructed. SED modeling was conducted to estimate the degree of infrared excess. It was found that a large majority of disks were optically thick accreting disks, suggesting that there has been little disk evolution in these sources. Nearest neighbor clustering analysis identified four small protostellar groups (L1228, L1228N, L1251A, and L1251B) with 5-15 members each and the larger NGC 7023 association with 32 YSO members. The star-Formation efficiency for cores with clusters of protostars and for those without clusters was found to be similar to 8% and similar to 1%, respectively. The cores L1155, L1241, and L1247 are confirmed to be starless down to our luminosity limit of L(bol) = 0.06 L(circle dot).